Certain types of work vehicles, such as skid steer loaders, bulldozers, and other crawler-type vehicles, include a dual-path electronically controlled hydrostatic transmission that is used for propulsion and steering of the vehicle. Specifically, the hydrostatic transmission typically includes an independent hydraulic pump and motor to drive each of the vehicle's left and right side drive components (e.g., left and right side wheels/tires or left and right side drive wheels/tracks). For example, a first hydraulic pump and motor may be provided for rotationally driving the vehicle's left side wheels while a separate hydraulic pump and motor may be provided for rotationally driving the vehicle's right side wheels. As such, the rotational speed of the left and right side wheels may be independently controlled, thereby allowing the vehicle to be steered. For example, by rotationally driving the left side wheels faster than the right side wheels, the work vehicle may be steered to the right. Similarly, by rotationally driving the right side wheels faster than the left side wheels, the work vehicle may be steered to the left.
Additionally, the operator of the work vehicle is typically provided with one or more input devices within the vehicle's cab, such as a left joystick and a right joystick, to provide independent control commands for regulating the drive speed of the left and right side drive components. For example, the operator may utilize the left joystick to provide suitable joystick commands for controlling the drive speed of the left side wheels and may utilize the right joystick to provide suitable joystick commands for controlling the drive speed of the right side wheels. In this regard, the operator may steer the work vehicle as it is being driven by adjusting the relative positioning of the left and right joysticks, thereby adjusting the relative drive speed of the left and right side wheels, respectively. Similarly, to drive the work vehicle along a straight path, the operator may move the left and right joysticks from their neutral position to the same forward or reverse position to provide equal joystick commands associated with driving the left and right side wheels at the same speed.
However, even when the operator commands that the work vehicle be driven along a straight path (e.g., by providing equal inputs via the left and right joysticks), the vehicle may veer to the left or right due to one or more factors, such as manufacturing tolerances, hydraulic driveline inefficiencies, “wear and tear” of the pump and motor components, loading conditions, differing tire sizes, etc. For instance, differences in the operating efficiencies between the left and right side pumps/motors may result in differing left/right side drive outputs despite the operator providing equal inputs into the system, thereby causing the vehicle to veer to the left or right. Similarly, even with equal drive outputs from the left and right side pumps/motors, the work vehicle may still veer to the left or right due to varying tire diameters between the left and right side tires (e.g., due to tire manufacturing tolerances and/or due to differing tire pressures). In this regard, prior art systems have been proposed that attempt to address this issue by allowing the drive output to the left and/or right side wheels to be adjusted, as necessary, to permit the work vehicle to track straight when so commanded by the operator. For example, known prior art systems allow an operator to manually input a trim adjustment that is directly applied to the joystick commands provided by the operator. However, despite such prior art systems, a need still exists for more efficient and/or effective systems for providing straight tracking control for a work vehicle having a dual-path, electronically controlled hydrostatic transmission.
Accordingly, an improved system and method for executing straight tracking control of a work vehicle to allow the vehicle to be driven along a straight path when so commanded by the operator would be welcomed in the technology.